Heterosis and combining ability for forage yield components in pearl millet, Pennisetum glaucum L.

Ten pollen parents of pearl millet were crossed with four male-sterile lines using line x tester mating design, The fourteen parents, 40 F1s and 40 F2s were grown to evaluate heterosis and combining ability in F I generation as well as inbreeding depression in F2 generation for forage yield and its related traits. Results showed significant differences among the evaluated genotypes for all studied traits of both cuts. Variable and significant magnitude of heterosis and heterobeltiosis was observed for all studied characters. The highest heterosis was expressed by plant height, number of tillers plant, fresh and dry forage yields at both cuts as well as total fresh and dry forage yields over the two cuts, The highest heterobeltiosis was observed for forage yield in the cross 861 A x 87/059IPCN0293 at both cuts. Estimates of variance component for general GCA and specific SCA combining abilities cleared the predominance of variance due to SCA over GCA, indicating non-additive type of gene action involved for the control of plant height, number of leaves/plant, stem diameter, leaf length, leaf width, number of tillers/plant, fresh and dry forage yields at both cuts as well as total fresh and dry yields over the two cuts, Seventeen of the crosses showed significant and favorable positive SCA effects for forage yield and its related traits. The crosses 861A x 87/059IPCN0293, ICMA98777 x ICMVO5111 and 14A x PEOO205 expressed significant positive SCA effects for total forage yield. Further 14A x PEOO205 and 17A x ICMVO5333 exhibited the best combinations for total dry forage yield. F2 crosses varied significantly for forage yield and its components. Some of evaluated F2 crosses showed close agreement between actual and predicted F2 yields indicating no epistasis, while other F2 crosses showed notable deviation between actual and predicted F2 yields indicating epistasis gene effects. For most studied characters, a large number of hybrids showed a significant positive and negative inbreeding depression